This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Our current work focuses on caspase-6 and -7. During this reporting period we worked on five main goals for understanding caspase-6 and -7. First, we have designed two new classes of active site inhibitors. We have crystals of caspase-6 with several of these active site inhibitors. Second, we have designed several mutations to probe the role of the structural changes in the 130's and 90's helix in caspase-6. Third, we have crystallized several versions of caspase-6 in a newly inactivated state. Together these structures will help us to understand and ultimately control caspase-6 in neurodegenerative diseases. Forth, we have grown crystals of caspase-7 with a number of novel active-site ligands. The aim of these studies is to understand the reaction mechanism in caspases. To date the molecular details of catalysis remain hazy because the only active site ligands that have been structurally characterized also distort the geometry around the catalytic diad. Fifth we have crystals of several new mutants of caspase-7 that are aimed at helping us to understand the interplay of caspase-7 active-site and allosteric-site regulation.